146 NORMAL HISTOLOGY. 



of grapes, in which the fruit would correspond to 

 the alveoli, the stem to the excretory ducts ; the 

 analogy failing at this point, however, for in the 

 gland the alveoli and ducts are bound together by 

 connective tissue lying between them called inter- 

 stitial tissue> in which the vessels and nerves ramify. 

 The alveoli which open into the same excretory 

 duct are usually joined more closely to one another 

 than to those opening into different ducts, and these 

 clusters of alveoli are called the lobules or acini of 

 the gland. Such are the mammary glands and cer- 

 tain mucous glands of the bronchi. 



3. Vesicular Glands. These consist of simple, 

 spheroidal, or irregular-shaped closed alveoli, sur- 

 rounded by a membrana propria, and lined with 

 epithelium, the second alveoli being imbedded in 

 interstitial connective tissue. Such glands are the 

 thyroid and ovary. 



THE STOMACH. 



The muscularis of the stomach differs from that 

 of the intestines, in that a certain number of the 

 cells, especially in the cardiac extremity, do not 

 have the typical transverse or longitudinal arrange- 

 ment, but lie in an oblique direction. In the vicinity 

 of the pylorus again, the inner circular layers are 

 much thickened, forming the sphincter pylori. The 

 mucosa is entirely made up of glands supported 

 and held together by a small amount of delicate 



